Exchangeable lens and camera body

ABSTRACT

An exchangeable lens includes: a mount unit at which a camera body is detachably engaged; a plurality of drive target members, conditions of which change as a drive force is applied thereto; an initialization unit that executes initialization processing for each of the plurality of drive target members; an initialization status transmission unit that transmits initialization statuses, each indicating a status of the initialization processing executed for one of the drive target members, to the camera body via a first transmission path over predetermined first cycles; and a drive condition transmission unit that transmits a drive condition of at least one drive target member among the plurality of drive target members to the camera body via a second transmission path different from the first transmission path over predetermined second cycles different from the predetermined first cycles.

This application is a continuation of U.S. application Ser. No.16/116,069 filed on Aug. 29, 2018, which is a continuation of U.S.application Ser. No. 15/691,081 filed on Aug. 30, 2017, which is acontinuation of U.S. application Ser. No. 15/292,684 filed Oct. 13,2016, which is a Divisional of U.S. application Ser. No. 14/945,063filed Nov. 18, 2015, which is a Continuation of U.S. application Ser.No. 14/697,215 filed Apr. 27, 2015, which is a Continuation of U.S.application Ser. No. 13/468,612 filed May 10, 2012, which is based uponand claims the benefit from U.S. Provisional Application No. 61/564,592filed Nov. 29, 2011, and Japanese Application No. 2011-108214 filed May13, 2011, the entire contents of the prior applications beingincorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an exchangeable lens and a camera body.

2. Description of Related Art

There are camera systems known in the related art comprise a camera bodyand an exchangeable lens that can be detachably mounted at the camerabody. Japanese Laid Open Patent Publication No. 2006-319631 discloses acamera system comprising a camera head at which a motor, used to drivevarious lenses, an aperture and the like are disposed, and a camerabody. At a camera head start up, initialization processing is firstexecuted in order to initialize the communication components and thenmain startup processing is executed to start the motor unit and an imagecapturing unit in this camera system.

SUMMARY OF THE INVENTION

There is an issue that needs to be addressed more effectively in thecamera system disclosed in the publication cited above, in that a timelag occurs at the camera body while the plurality of units are allstarted up at the camera head, which delays the process of camera headinitialization.

An exchangeable lens according to a 1st aspect of the present invention,comprises: a mount unit at which a camera body is detachably engaged; aplurality of drive target members, conditions of which change as a driveforce is applied thereto; an initialization unit that executesinitialization processing for each of the plurality of drive targetmembers; an initialization status transmission unit that transmitsinitialization statuses, each indicating a status of the initializationprocessing executed for one of the drive target members, to the camerabody via a first transmission path over predetermined first cycles; anda drive condition transmission unit that transmits a drive condition ofat least one drive target member among the plurality of drive targetmembers to the camera body via a second transmission path different fromthe first transmission path over predetermined second cycles differentfrom the predetermined first cycles.

An exchangeable lens according to a 2nd aspect of the present inventioncomprises: a mount unit at which a camera body is detachably engaged; aplurality of drive target members, conditions of which change as a driveforce is applied thereto; an initialization unit that executesinitialization processing for each of the plurality of drive targetmembers; an initialization status transmission unit that transmitsinitialization statuses, each indicating a status of the initializationprocessing executed for one of the drive target members, to the camerabody via a first transmission path over predetermined first cycles; anda drive condition transmission unit that transmits position informationrelated to a position of at least one drive target member among theplurality of drive target members to the camera body via a secondtransmission path different from the first transmission path overpredetermined second cycles different from the predetermined firstcycles.

An exchangeable lens according to a 3rd aspect of the present inventioncomprises: a mount unit at which a camera body is detachably engaged; adrive target member, a condition of which changes as a drive force isapplied thereto; an initialization unit that executes initializationprocessing for the drive target member; an initialization statustransmission unit that transmits an initialization status indicating astatus of the initialization processing executed for the drive targetmember to the camera body via a first transmission path overpredetermined first transmission cycles; and a drive conditiontransmission unit that transmits position information related to aposition of the drive target member, to the camera body via a secondtransmission path different from the first transmission path overpredetermined second cycles different from the predetermined firstcycles.

According to a 4th aspect of the present invention, in the exchangeablelens according to the 1st or 2nd aspect, it is preferable that after achange occurs in the initialization status of at least one drive targetmember among the plurality of drive target members, the drive conditiontransmission unit starts transmitting the drive condition of the drivetarget member, the initialization status of which has changed.

According to a 5th aspect of the present invention, in the exchangeablelens according to the 4th aspect, it is preferable that after theinitialization statuses of all the drive target members for whichinitialization processing is executed by the initialization unit change,the drive condition transmission unit starts transmitting at least thedrive condition of the one drive target member.

According to a 6th aspect of the present invention, in the exchangeablelens according to the 4th or 5th aspect, the initialization unit maystart executing initialization processing for all the drive targetmembers at once.

According to a 7th aspect of the present invention, in the exchangeablelens according to any one of the 4th through 6th aspects, it ispreferable that one of the drive target members is an aperture; and theinitialization unit completes initialization processing for the apertureahead of the initialization processing for another drive target member.

According to a 8th aspect of the present invention, in the exchangeablelens according to the 7th aspect, it is preferable that until theinitialization unit completes initialization processing for theaperture, the initialization status transmission unit transmits theinitialization status information indicating that the initializationprocessing for a drive target member other than the aperture is notcomplete.

According to a 9th aspect of the present invention, in the exchangeablelens according to the 4th or 5th aspect, the initialization unit mayinitialize the drive target members in a predetermined order byexecuting the initialization processing for one drive target member at atime.

A camera body according to a 10th aspect of the present inventioncomprises: a mount unit at which an exchangeable lens is detachablymounted, with the exchangeable lens being equipped with a plurality ofdrive target members, drive conditions of which change as a drive forceis applied thereto; an initialization status reception unit thatreceives initialization statuses, each indicating a status of specificinitialization processing executed at the exchangeable lens for one ofthe drive target members, from the exchangeable lens via a firsttransmission path over first cycles; and a drive condition receptionunit that receives a drive condition of at least one drive target memberamong the plurality of drive target members from the exchangeable lensvia a second transmission path different from the first transmissionpath over second cycles different from the first cycles.

According to a 11th aspect of the present invention, in the camera bodyaccording to the 10th aspect, it is preferable that after detecting achange in at least the initialization status of the one drive targetmember, the drive condition reception unit starts receiving the drivecondition of the drive target member the initialization status of whichhas changed.

According to a 12th aspect of the present invention, in the camera bodyaccording to the 10th or 11th aspect, it is preferable that after theinitialization statuses of all the drive target members for which theinitialization processing is executed at the exchangeable lens change,the drive condition reception unit starts receiving at least the drivecondition of the one drive target member.

According to a 13th aspect of the present invention, the camera bodyaccording to any one of the 10th through 12th aspect may furthercomprise: a control unit that enables specific control processing to beexecuted for each of the plurality of drive target members, wherein: thecontrol unit does not allow the control processing to be executed forany drive target member, execution of the initialization processing forwhich is indicated to be incomplete in the initialization status data.

According to a 14th aspect of the present invention, in the camera bodyaccording to the 13th aspect, it is preferable that one of the drivetarget members is an aperture; and the control unit enables aperturecontrol processing to be executed for the aperture as the controlprocessing.

An exchangeable lens according to a 15th aspect of the present inventioncomprises: a mount unit at which a camera body is detachably engaged; adrive target member, a condition of which changes as a drive force isapplied thereto; an initialization unit that executes initializationprocessing for the drive target member; and a transmission unit thattransmits an initialization status indicating a status of theinitialization processing to the camera body in response to a requestoutput from the camera body over first cycles.

According to a 16th aspect of the present invention, the exchangeablelens according to the 15th aspect may further comprise: a drivecondition transmission unit that transmits a drive condition of thedrive target member to the camera body via a second transmission pathdifferent from the first transmission path in response to a requestoutput from the camera body over second cycles different from the firstcycles, wherein: the drive condition transmission unit startstransmitting the drive condition of the drive target member afterinitialization of the drive target member is completed.

According to a 17th aspect of the present invention, in the exchangeablelens according to the 15th or 16th aspect, it is preferable that theexchangeable lens includes a plurality of drive target members; and theinitialization unit starts executing the initialization processing forthe plurality of drive target members at once.

According to a 18th aspect of the present invention, in the exchangeablelens according to the 17th aspect, it is preferable that afterinitialization of all the drive target members for which theinitialization processing is executed by the initialization unit iscompleted, the drive condition transmission unit starts transmitting thedrive condition of at least one drive target member among the pluralityof drive target members.

An exchangeable lens according to a 19th aspect of the present inventioncomprises: a mount unit at which a camera body is detachably engaged; aplurality of drive target members, conditions of which change as a driveforce is applied thereto; an initialization unit that executesinitialization processing for each of the plurality of drive targetmembers; an initialization status transmission unit that transmitsinitialization statuses, each indicating a status of the initializationprocessing executed for one of the drive target members, to the camerabody via a first transmission path in response to a request output fromthe camera body over first cycles; and a drive condition transmissionunit that transmits a drive condition of at least one drive targetmember among the plurality of drive target members to the camera bodyvia a second transmission path different from the first transmissionpath in response to a request output from the camera body over secondcycles different from the first cycles, wherein: after a change occursat least in the initialization status of the one drive target member,the drive condition transmission unit starts transmitting the drivecondition of the drive target member, the initialization status of whichhas changed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of a camera system compatible with exchangeablelenses, in which the present invention is adopted.

FIG. 2 is a sectional view of the camera system compatible withexchangeable lenses, in which the present invention is adopted.

FIG. 3 is a schematic diagram showing in detail holding portions.

FIG. 4 is a timing chart indicating the timing with which command datacommunication may be executed.

FIGS. 5A and 5B are timing charts indicating the timing with whichhotline communication may be executed.

FIGS. 6A and 6B show the structure of initialization status data.

FIG. 7 is a timing chart indicating a procedure through whichinitialization is executed following a power on.

FIG. 8 shows the structure of the drive conditions data.

FIG. 9 presents a flowchart of the processing executed at the camerabody and the exchangeable lens during a period following a power onoperation and preceding a point at which a photographing-enabled stateis achieved.

FIG. 10 is a timing chart indicating a procedure through whichinitialization is executed following a power on.

DESCRIPTION OF PREFERRED EMBODIMENTS First Embodiment

FIG. 1 is a perspective of a camera system compatible with exchangeablelenses, in which the present invention is adopted. It is to be notedthat FIG. 1 only shows the units and devices relevant to the presentinvention and that an illustration and an explanation of other units anddevices are not provided. A camera 1 comprises a camera body 100 and anexchangeable lens (also referred to as an interchangeable lens or aphotographic lens) 200 that can be detachably mounted at the camera body100.

The camera body 100 includes a lens mount 101 at which the exchangeablelens 200 is detachably mounted. A holding portion (electrical connectorportion) 102, a part which projects out toward the inner circumferentialside of the lens mount 101, with contact points held thereat, isdisposed at the camera body 100 in an area near the lens mount 101 (onthe inner circumferential side of the lens mount 101). A plurality ofcontact points are present at the holding portion 102 (see FIG. 3).

In addition, a lens mount 201, corresponding to the body-side lens mount101, at which the camera body 100 is detachably engaged, is disposed atthe exchangeable lens 200. A holding portion (electrical connectorportion) 202, a part which projects out toward the inner circumferentialside of the lens mount 201 with contact points held thereat, is disposedat the exchangeable lens 200 in an area near the lens mount 201 (on theinner circumferential side of the lens mount 201). A plurality ofcontact points are present at the holding portion 202 (see FIG. 3).

As the exchangeable lens 200 is engaged with the camera body 100, theholding portion 102 with a plurality of contact points held thereatbecomes electrically and physically connected with the holding portion202 holding a plurality of contact points. Via the two holding portions102 and 202, power is provided from the camera body 1000 to theexchangeable lens 200 and signals are exchanged between the camera body100 and the exchangeable lens 200.

An image sensor 104, which may be, for instance, a CMOS image sensor ora CCD image sensor, is disposed inside the camera body 100 at a positionrearward relative to the lens mount 101. A button 107, functioning as aninput device is disposed on the top side of the camera body 100. Theuser is able to issue a photographing instruction, a photographingcondition setting instruction or the like to the camera body 100 byoperating an input device such as the button 107.

FIG. 2 is a sectional view of the camera system compatible withexchangeable lenses, in which the present invention is adopted. Theexchangeable lens 200 includes an image forming optical system 210 viawhich a subject image is formed. The image forming optical system 210 isconstituted with a plurality of lenses 210 a through 210 c and anaperture 211. The plurality of lenses 210 a through 210 c includes afocusing lens 210 b used to control the focus position for the subjectimage and a blur correction lens 210 c via which an image blur occurringin the subject image is corrected.

A lens control unit 203, which controls the various componentsconstituting the exchangeable lens 200, is disposed inside theexchangeable lens 200. The lens control unit 203 comprises amicrocomputer, its peripheral circuits and the like (none shown). Afirst lens-side communication unit 217, a second lens-side communicationunit 218, a focusing lens drive unit 212, a blur correction lens driveunit 213, an aperture drive unit 214, a ROM 215 and a RAM 216 areconnected to the lens control unit 203.

The first lens-side communication unit 217 and the second lens-sidecommunication unit 218 exchange data with the camera body 100 viacommunication contact points at the holding portions 102 and 202. Thefirst lens-side communication unit 217 and the second lens-sidecommunication unit 218 each function as a communication interface forthe exchangeable lens 200. The lens control unit 203 engages in varioustypes of communication (hotline communication and command datacommunication) with the camera body 100 (with a body control unit 103 tobe described in detail later) via these communication interfaces.

The focusing lens drive unit 212, which includes an actuator such as astepping motor, drives the focusing lens 210 b in response to a signalinput to the focusing lens drive unit 212. Likewise, the blur correctionlens drive unit 213 and the aperture drive unit 214, each equipped withan actuator such as a voice coil motor, respectively drive the blurcorrection lens 210 c and the aperture 211 in response to signals inputthereto.

The focusing lens 210 b is driven along the optical axis by the focusinglens drive unit 212. The blur correction lens 210 c is driven by theblur correction lens drive unit 213 along a direction (X direction, Ydirection) perpendicular to the optical axis. The aperture 211 is drivenby the aperture drive unit 214 so as to alter the size (openingdiameter) of the opening through which subject light is allowed to pass.Namely, these members are drive target members, the drive conditions ofwhich change as they are driven with drive forces imparted from thecorresponding drive units. The term “drive condition” used in thiscontext refers to a condition, among the conditions inherent to eachdrive target member, which changes as the particular drive target memberis driven. For instance, a drive condition of the focusing lens 210 bmay be its position assumed along the optical axis, a drive condition ofthe blur correction lens 210 c may be its position assumed on a planeperpendicular to the optical axis, and a drive condition of the aperture211 may be its opening diameter (and the F number of the image formingoptical system 210, which changes in correspondence to the openingdiameter).

It is to be noted that a drive target member other than the drive targetmembers listed above (the focusing lens 210 b, the blur correction lens210 c, and the aperture 211) may be disposed in the exchangeable lens200. For instance, a zoom lens, which is allowed to move along theoptical axis of the image forming optical system 210, as is the focusinglens 210 b, may be included in the exchangeable lens 200, together witha mechanism (known as a power zoom mechanism) that electrically drivesthe zoom lens, also disposed in the exchangeable lens 200.

The ROM 215 is a nonvolatile storage medium into which a specificcontrol program, to be executed by the lens control unit 203, and thelike are stored in advance. The RAM 216 is a volatile storage mediumused by the lens control unit 203 as a storage area where various typesof data are stored.

The lens control unit 203 includes an initialization status transmissionunit 221, a drive condition transmission unit 222 and an initializationcontrol unit 223 embodied in software. These functional units areachieved in software as the lens control unit 203 executes the specificcontrol program stored in the ROM 215.

The initialization control unit 223 executes a specific type ofinitialization processing for each of the plurality of drive targetmembers listed above. The initialization status transmission unit 221transmits, through a first transmission path (to be described in detaillater), initialization status data (e.g., status data indicating whetherthe execution of the initialization processing has been completed or theinitialization processing execution is not yet completed), indicating aninitialization processing status for each of the plurality of drivetarget members, to the camera body 100 over predetermined cycles. Thedrive condition transmission unit 222 transmits, through a secondtransmission path (to be described in detail later) different from thefirst transmission path, drive condition data indicating the driveconditions of the drive target members described above to the camerabody over predetermined cycles. The procedure through which theinitialization status transmission unit 221 transmits the initializationstatus data to the camera body 100 over the predetermined cycles is nowdescribed. The camera body 100 keeps outputting a command requestinginitialization status data to the exchangeable lens 200 overpredetermined cycles until it receives a signal indicating completion ofthe initialization processing from the exchangeable lens 200. Inresponse to this request command, the initialization status transmissionunit 221 in the exchangeable lens 200 returns prepared initializationstatus data. Through this sequence, the initialization statustransmission unit 221 transmits the initialization status data to thecamera body 100 over the predetermined cycles.

A shutter 115, via which the exposure conditions at the image sensor 104are controlled, and an optical filter 116, which is an integrated filterachieved by combining an optical low pass filter and an infrared cut-offfilter, are disposed in front of the image sensor 104. The subject lighthaving been transmitted through the image forming optical system 210enters the image sensor 104 via the shutter 115 and the filter 116.

The body control unit 103, engaged in control of the various componentsof the camera body 100, is disposed inside the camera body 100. The bodycontrol unit 103 is constituted with a microcomputer, a RAM, peripheralcircuits and the like (none shown).

A first body-side communication unit 117 and a second body-sidecommunication unit 118 are connected to the body control unit 103. Thefirst body-side communication unit 117 is connected to the holdingportion 102 and is able to exchange data with the first lens-sidecommunication unit 217 via a contact point held at the holding portion102. The second body-side communication unit 118 is likewise able toexchange data with the second lens-side communication unit 218. Namely,the first body-side communication unit 117 and the second body-sidecommunication unit 118 each function as a body-side communicationinterface. The body control unit 103 engages in various types ofcommunication (hotline communication and command data communication)with the exchangeable lens 200 (with the lens control unit 203) viathese communication interfaces.

A display device 111 constituted with an LCD panel or the like isdisposed at the rear surface of the camera body 100. The body controlunit 103 brings up on display at the display device 111 a subject image(referred to as a live view image) based upon an output from the imagesensor 104 or various types of menu screens enabling selection ofphotographing conditions and the like.

The body control unit 103 includes an initialization status receptionunit 121, a drive condition reception unit 122 and a drive control unit123 embodied in software. These functional units are each achieved insoftware as the body control unit 103 executes a specific controlprogram. The initialization status reception unit 121 receives theinitialization status data transmitted by the initialization statustransmission unit 221. The drive condition reception unit 122 receivesthe drive condition data indicating the drive conditions at the drivetarget members, which are transmitted by the drive conditiontransmission unit 222. Based upon the initialization status datareceived via the initialization status reception unit 121, the drivecontrol unit 123 executes control processing (to be described later) foreach of the drive target members.

Description of the Holding Portions 102 and 202

FIG. 3 is a schematic diagram showing structural details of the holdingportions 102 and 202. It is to be noted that FIG. 3 shows the holdingportion 102 set to the right of the lens mount 101, as in the actualmount structure. Namely, the holding portion 102 achieved in theembodiment is disposed at a position inward relative to the mountsurface of the lens mount 101 at the camera body 100 (to the right ofthe lens mount 101 in FIG. 3). Likewise, the holding portion 202 in thefigure assumes a position to the right of the lens mount 201 to indicatethat the holding portion 202 in the embodiment is disposed at a positionoutward relative to the mount surface of the lens mount 201 at theexchangeable lens 200. The holding portion 102 and the holding portion202 disposed with this positional arrangement become connected with eachother and the electrical contact points at these holding portions, too,become connected as the camera body 100 and the exchangeable lens 200are engaged with each other via their mounts by placing the mountsurface of the lens mount 101 and the mount surface of the lens mount201 in contact with each other. Since this mount structure is of theknown art, a further explanation or illustration is not provided.

As shown in FIG. 3, twelve contact points BP1 through BP12 are presentat the holding portion 102. In addition, twelve contact points LP1through LP12, each corresponding to one of the twelve contact points atthe holding portion 102, are present at the holding portion 202.

The contact point BP1 and the contact point BP2 are connected to a firstpower source circuit 130 located in the camera body 100. The first powersource circuit 130 provides an drive voltage to the contact point BP1,via which the drive voltage is supplied to various components disposedin the exchangeable lens 200 except for circuits such as the focusinglens drive unit 212, the blur correction lens drive unit 213 and theaperture drive unit 214, equipped with drive systems, e.g., actuators,that are bound to consume large amounts of power. In other words, andrive voltage on which the various components in the exchangeable lens200 except for the drive units listed above are to operate, is providedvia the contact point BP1 and the contact point LP1. While a specificrange (e.g., a voltage range from equal to or larger than 3 to less than4 v) defined by a minimum voltage value and a maximum voltage value, isassumed for the voltage value representing the level of voltage that canbe provided to the contact point BP1, the voltage value of the voltagetypically provided to the contact point BP1 is close to the median ofthe maximum voltage value and the minimum voltage value. The value ofthe electrical current provided from the camera body 100 to theexchangeable lens 200 in conjunction with the drive voltage will be inthe range of approximately several tens of mA to several hundreds of mAin a power on state.

The contact point BP2 is a ground terminal that corresponds to the drivevoltage provided to the contact point BP1. Namely, the contact point BP2and the contact point LP2 are ground terminals that correspond to thedrive voltage.

In the following description, the signal line formed with the contactpoint BP1 and the contact point LP1 will be referred to as a signal lineV33. The signal line formed with the contact point BP2 and the contactpoint LP2 will be referred to as a signal line GND. These contact pointsLP1, LP2, BP1 and BP2 are power source-system contact points used toprovide power from the camera body 100 to the exchangeable lens 200.

The contact points BP3, BP4, BP5 and BP6 are connected to the firstbody-side communication unit 117. The contact points LP3, LP4, LP5 andLP6 at the exchangeable lens 200, corresponding to the contact pointsBP3, BP4, BP5 and BP6, are connected to the first lens-sidecommunication unit 217. The first body-side communication unit 117 andthe first lens-side communication unit 217 exchange data with each othervia these contact points (communication-system contact points). Thecommunication carried out by the first body-side communication unit 117and the first lens-side communication unit 217 will be described indetail later.

It is to be noted that the signal line formed with the contact point BP3and the contact point LP3 will be referred to as a signal line CLK. Inaddition, the signal line formed with the contact point BP4 and thecontact point LP4 will be referred to as a signal line BDAT, the signalline formed with the contact point BP5 and the contact point LP5 will bereferred to as a signal line LDAT and the signal line formed with thecontact point BP6 and the contact point LP6 will be referred to as asignal line RDY.

The contact points BP7, BP8, BP9 and BP10 are connected to the secondbody-side communication unit 118. The contact points LP7, LP8, LP9 andLP10 at the exchangeable lens 200, corresponding to the contact pointsBP7, BP8, BP9 and BP10, are connected to the second lens-sidecommunication unit 218. The second lens-side communication unit 218transmits data to the second body-side communication unit 118 via thesecontact points (communication system contact points). The communicationcarried out by the second body-side communication unit 118 and thesecond lens-side communication unit 218 will be described in detaillater.

It is to be noted that the signal line formed with the contact point BP7and the contact point LP7 will be referred to as a signal line HREQ. Inaddition, the signal line formed with the contact point BP8 and thecontact point LP8 will be referred to as a signal line HANS, the signalline formed with the contact point BP9 and the contact point LP9 will bereferred to as a signal line HCLK and the signal line formed with thecontact point BP10 and the contact point LP10 will be referred to as asignal line HDAT.

The contact point BP11 and the contact point BP12 are connected to asecond power source circuit 131 located in the camera body 100. Thesecond power source circuit 131 provides a drive voltage to the contactpoint BP12, via which the drive voltage is supplied to circuits, such asthe focusing lens drive unit 212, the blur correction lens drive unit213 and the aperture drive unit 214, equipped with drive systems, e.g.,actuators, that are bound to consume large amounts of power. In otherwords, the drive voltage for the focusing lens drive unit 212, the blurcorrection lens drive unit 213 and the aperture drive unit 214 issupplied via the contact point BP12 and the contact point LP12. Whilethe voltage value indicating the level of voltage that can be providedto the contact point BP12 assumes a range defined by a minimum voltagevalue and a maximum voltage value, the voltage value is never smallerthan the voltage value indicating the level of voltage that can beprovided to the contact point BP1 assuming its own specific voltagevalue range as has been explained earlier (for instance, the maximumvoltage value indicating the highest level of voltage that can beprovided to the contact point BP12 may be several times the maximumvoltage value indicating the highest level of voltage that can besupplied to the contact point BP1). In other words, the voltage valueindicating the level of voltage provided to the contact point BP12 isalways different from the voltage value indicating the level of voltageprovided to the contact point BP1. It is to be noted that the voltagevalue indicating the level of voltage provided to the contact point BP12under normal circumstances is close to the median of the maximum voltagevalue and the minimum voltage value assumed for the contact point BP12.The value of the electrical current provided from the camera body 100 tothe exchangeable lens 200 in conjunction with the drive voltage will bein the range of approximately several tens of mA to several A in thepower on state.

The contact point BP11 is a ground terminal that corresponds to thedrive voltage provided to the contact point BP12. Namely, the contactpoint BP11 and the contact point LP11 are ground terminals thatcorrespond to the drive voltage.

In the following description, the signal line formed with the contactpoint BP11 and the contact point LP11 will be referred to as a signalline PGND. The signal line formed with the contact point BP12 and thecontact point LP12 will be referred to as a signal line BAT. Thesecontact points LP11, LP12, BP11 and BP12 are power source-system contactpoints used to provide power from the camera body 100 to theexchangeable lens 200.

It is to be noted that as the varying ranges assumed for the voltagevalue (current value) indicating the level of voltage provided via thecontact point BP12 and the contact point LP12 and for the voltage value(current value) indicating the level of voltage provided via the contactpoint BP1 and LP1 clearly indicate, the difference between the maximumvalue and the minimum value taken for the electric current flowingthrough the contact point BP11 and the contact point LP11, i.e., throughthe ground terminals corresponding to the voltage provided through thecontact points BP12 and LP12, is greater than the difference between themaximum value and the minimum value taken for the electric currentflowing through the contact point BP2 and the contact point LP2, i.e.,the ground terminals corresponding to the voltage provided through thecontact points BP1 and LP1. A greater difference is assumed between themaximum value and the minimum value taken for the electric currentflowing through the contact points BP11 and LP11, since greater power isused in the various drive units each equipped with a drive system suchas an actuator, compared to the power used in the electronic circuits,e.g., the lens control unit 203, in the exchangeable lens 200 and also,a given drive unit does not use any power at all if it does not need todrive the corresponding drive target member.

Description of Command Data Communication

The lens control unit 203, concurrently receives control data from thefirst body-side communication unit 117 and transmits response data tothe first body-side communication unit 117 over predetermined firstcycles (16 ms cycles in the embodiment) via the contact points LP3through LP6, i.e., via the signal lines CLK, BDAT, LDAT and RDY, bycontrolling the first lens-side communication unit 217. The following isa detailed description of the communication carried out by the firstlens-side communication unit 217 and the first body-side communicationunit 117.

It is to be noted that in the description of the embodiment, thecommunication carried out by the first lens-side communication unit 217and the first body-side communication unit 117 respectively undercontrol executed by the lens control unit 203 and the body control unit103 will be referred to as “command data communication”. In addition,the transmission path constituted with the four signal lines used forcommand data communication (the signal lines CLK, BDAT, LDAT and RDY)will be referred to as a first transmission path. The communicationsystem engaged in command data communication will be referred to as a“command data communication system”.

FIG. 4 is a timing chart indicating the timing with which command datacommunication may be executed. The body control unit 103 and the firstbody-side communication unit 117 verify the signal level at the signalline RDY at a command data communication start (T1). The signal level atthe signal line RDY indicates whether or not the first lens-sidecommunication unit 217 is in a communication-enabled state. If the firstlens-side communication unit 217 is in a communication disabled state,the lens control unit 203 and the first lens-side communication unit 217output an H (high) level signal through the contact point LP6. In otherwords, the signal level at the signal line RDY is set to H. Until thesignal line RDY holding H level shifts to L level, the body control unit103 and the first body-side communication unit 117 do not startcommunication. They do not execute the next phase of processing for anycommunication in progress either.

Upon verifying that the signal level at the signal line RDY is L (low)level, the body control unit 103 and the first body-side communicationunit 117 output a clock signal 401 through the contact point BP3.Namely, the clock signal 401 is transmitted to the first lens-sidecommunication unit 217 through the signal line CLK. In synchronizationwith the clock signal 401, the body control unit 103 and the firstbody-side communication unit 117 output a body-side command packetsignal 402, which constitutes the first half of control data, via thecontact point BP4. Namely, the body-side command packet signal 402 istransmitted to the first lens-side communication unit 217 via the signalline BDAT.

In addition, in synchronization with the clock signal 401 output to thesignal line CLK, the lens control unit 203 and the first lens-sidecommunication unit 217 output a lens-side command packet signal 403,which constitutes the first half of response data, via the contact pointLP5. Namely, the lens-side command packet signal 403 is transmitted tothe first body-side communication unit 117 via the signal line LDAT.

Upon completion of the transmission of the lens-side command packetsignal 403, the lens control unit 203 and the first lens-sidecommunication unit 217 set the signal level at the signal line RDY to H(T2). The lens control unit 203 then starts first control processing 404(which will be described later) corresponding to the contents of thebody-side command packet signal 402 having been received.

Upon completing the first control processing 404, the lens control unit203 notifies the first lens-side communication unit 217 of completion ofthe first control processing 404. In response to this notification, thefirst lens-side communication unit 217 outputs an L-level signal via thecontact point LP6. In other words, the signal level at the signal lineRDY is set to L (T3). In response to the signal level shift, the bodycontrol unit 103 and the first body-side communication unit 117 output aclock signal 405 through the contact point BP3. Namely, the clock signal405 is transmitted to the first lens-side communication unit 217 via thesignal line CLK.

In synchronization with the clock signal 405, the body control unit 103and the first body-side communication unit 117 output a body-side datapacket signal 406, which constitutes the second half of the controldata, via the contact point BP4. Namely, the body-side data packetsignal 406 is transmitted to the first lens-side communication unit 217via the signal line BDAT.

In addition, in synchronization with the clock signal 405 output to thesignal line CLK, the lens control unit 203 and the first lens-sidecommunication unit 217 output a lens-side data packet signal 407, whichconstitutes the second half of the response data, via the contact pointLP5. Namely, the lens-side data packet signal 407 is transmitted to thefirst body-side communication unit 117 via the signal line LDAT.

Upon completion of the transmission of the lens-side data packet signal407, the lens control unit 203 and the first lens-side communicationunit 217 set the signal level at the signal line RDY to H again (T4).The lens control unit 203 then starts second control processing 408(which will be described later) corresponding to the contents of thebody-side data packet signal 406 having been received.

The first control processing 404 and the second control processing 408executed by the lens control unit 203 are described next.

The body-side command packet signal 402 may be a request to the exchangelens side for specific data. In such a case, the lens control unit 203analyzes the contents of the command packet signal 402 and generates therequested specific data through the first control processing 404.Furthermore, as part of the first control processing 404, the lenscontrol unit 203 executes abridged communication error check processingbased upon the number of data bytes so as to determine whether or notthere has been any error in the communication of the command packetsignal 402 by using checksum data contained in the command packet signal402. The signal carrying the specific data generated through the firstcontrol processing 404 is output as the lens-side data packet signal 407to the body side. It is to be noted that the body-side data packetsignal 406 output from the body side following the initial output of thecommand packet signal 402 in this situation is a dummy data signal(still containing checksum data) which does not carry any significanceto the lens side. Under these circumstances, the lens control unit 203executes communication error check processing such as that describedabove, by using the checksum data contained in the body-side data packetsignal 406 as the second control processing 408.

In another scenario, the body-side command packet signal 402 may be adrive instruction for driving a lens-side drive target member. Forinstance, the command packet signal 402 may be a drive instruction forthe focusing lens 210 b and the body-side data packet signal 406 mayindicate a drive quantity, i.e., the extent to which the focusing lens210 b needs to be driven. In this case, the lens control unit 203analyzes the contents of the command packet signal 402 and generates anOK signal acknowledging that the contents have been understood.Furthermore, as part of the first control processing 404, the lenscontrol unit 203 executes communication error check processing asdescribed above by using the checksum data carried in the command packetsignal 402. The OK signal generated through the first control processing404 is then output to the body side as the lens-side data packet signal407. In addition, the lens control unit 203 analyzes the contents of thebody-side data packet signal 406 and executes communication error checkprocessing, such as that described above, by using the checksum datacontained in the body-side data packet signal 406 in the second controlprocessing 408.

Upon completing the second control processing 408, the lens control unit203 notifies the first lens-side communication unit 217 of completion ofthe second control processing 408. By issuing this notification, thelens control unit 203 prompts the first lens-side communication unit 217to output an L-level signal through the contact point LP6. Namely, thesignal level at the signal line RDY is set to L (T5).

It is to be noted that if the body-side command packet signal 402 is aninstruction for driving a lens-side drive target member (e.g., thefocusing lens) as described above, the lens control unit 203 engages thefocusing lens drive unit 212 in execution of processing through whichthe focusing lens 210 b is driven by the extent matching the drivequantity, while sustaining the signal level at the signal line RDY at Llevel via the first lens-side communication unit 217.

The communication carried out from the time point T1 through the timepoint T5 as described above constitutes a single command datacommunication session. Through the single session of command datacommunication executed as described above, one body-side command packetsignal 402 and one body-side data packet signal 406 are transmitted bythe body control unit 103 and the first body-side communication unit117. Namely, while the processing requires two separate packet signalsto be transmitted, the two separate packet signals, i.e., the body-sidecommand packet signal 402 and the body-side data packet signal 406,together constitute a set of control data.

Likewise, one lens-side command packet signal 403 and one lens-side datapacket signal 407 are transmitted by the lens control unit 203 and thefirst lens-side communication unit 217. Namely, the two separate packetsignals, i.e., the lens-side command packet signal 403 and the lens-sidedata packet signal 407, together constitute a set of response data.

As described above, the lens control unit 203 and the first lens-sidecommunication unit 217 receive the control data from the first body-sidecommunication unit 117 and concurrently transmit the response data tothe first body-side communication unit 117. The contact point LP6 andthe contact point BP6 used for command data communication are contactpoints via which an asynchronous signal (a signal indicating H (high)level or L (low) level read at the signal line RDY), which is notsynchronous with any clock signal, is transmitted.

Description of Hotline Communication

The lens control unit 203 transmits lens position data to the secondbody-side communication unit 118 via the contact point LP7 through LP10,i.e., via the signal lines HREQ, HANS, HCLK and HDAT, by controlling thesecond lens-side communication unit 218. The following is a detaileddescription of the communication carried out by the second lens-sidecommunication unit 218 and the second body-side communication unit 118.

It is to be noted that in the description of the embodiment, thecommunication carried out by the second lens-side communication unit 218and the second body-side communication unit 118 respectively undercontrol executed by the lens control unit 203 and the body control unit103 will be referred to as “hotline communication”. In addition, thetransmission path constituted with the four signal lines used for thehotline communication (the signal lines HREQ, HANS, HCLK and HDAT) willbe referred to as a second transmission path. The communication systemengaged in hotline communication will be referred to as a “hotlinecommunication system”.

FIGS. 5A and 5B are timing charts indicating the timing with whichhotline communication may be executed. The body control unit 103 in theembodiment adopts a structure that allows it to start hotlinecommunication over predetermined second cycles (1 ms cycles in theembodiment). These cycles are shorter than the cycles over which commanddata communication is executed. FIG. 5A indicates that hotlinecommunication is repeatedly executed over predetermined cycles Tn. FIG.5B is an enlarged view of a given communication period Tx elapsing ashotline communication is repeatedly executed. The following is adescription of the procedure through which hotline communication iscarried out, given in reference to the timing chart in FIG. 5B.

The body control unit 103 and the second body-side communication unit118 first output an L-level signal through the contact point BP7 at ahotline communication start (T6). In other words, the signal level atthe signal line HREQ is set to L. The second lens-side communicationunit 218 notifies the lens control unit 203 that the signal has beeninput to the contact point LP7. In response to this notification, thelens control unit 203 starts executing data generation processing 501 inorder to generate lens position data. Through the generation processing501, the lens control unit 203 engages a focusing lens positiondetection unit (not shown) in detection of the position of the focusinglens 210 b and generates lens position data indicating the detectionresults.

Once the lens control unit 203 completes execution of the generationprocessing 501, the lens control unit 203 and the second lens-sidecommunication unit 218 output an L-level signal through the contactpoint LP8 (T7). In other words, the signal level at the signal line HANSis set to L. In response to input of this signal at the contact pointBP8, the body control unit 103 and the second body-side communicationunit 118 output a clock signal 502 via the contact point BP9. Namely,the clock signal is transmitted to the second lens-side communicationunit 218 via the signal line HCLK.

In synchronization with the clock signal 502, the lens control unit 203and the second lens-side communication unit 218 output a lens positiondata signal 503 carrying the lens position data through the contactpoint LP10. In other words, the lens position data signal 503 istransmitted to the second body-side communication unit 118 via thesignal line HDAT.

Upon completing the transmission of the lens position data signal 503,the lens control unit 203 and the second lens-side communication unit218 output an H-level signal through the contact point LP8. In otherwords, the signal level at the signal line HANS is set to H (T8). Inresponse to input of this signal at the contact point BP8, the secondbody-side communication unit 118 outputs an H-level signal through thecontact point LP7. In other words, the signal level at the signal lineHREQ is set to H (T9).

The communication carried out from the time point T6 through the timepoint T9 as described above constitutes a single hotline communicationsession. Through the single session of hotline communication executed asdescribed above, a single lens position data signal 503 is transmittedby the lens control unit 203 and the second lens-side communication unit218. The contact points LP7, LP8, BP7 and BP8, used in hotlinecommunication are contact points via which asynchronous signals, whichare not synchronous with any clock signal, are transmitted. In otherwords, the contact points LP7 and BP7 are contact point via which anasynchronous signal (indicating H (high) level or L (low) level read atthe signal line HREQ) is transmitted, whereas the contact points LP8 andBP8 are contact point via which an asynchronous signal (indicating H(high) level or L (low) level read at the signal line HANS) istransmitted.

It is to be noted that command data communication and hotlinecommunication may be executed simultaneously or they may be executedpartially concurrently. This means that even while one of thecommunication units, i.e., the first lens-side communication unit 217and the second lens-side communication unit 218, is engaged incommunication with the camera body 100, the other communication unit isalso allowed to communicate with the camera body 100.

Description of Processing Executed After Power On

Following a power on operation performed by the user to turn the camera1 on (by, for instance, operating a power switch (not shown)), the lenscontrol unit 203 (the initialization control unit 223) executesinitialization processing to initialize the various components of theexchangeable lens 200. At this time, the body control unit 103 alsoexecutes initialization processing to initialize the various componentsdisposed at the camera body 100.

The lens control unit 203 (initialization control unit 223) executingthe initialization processing first initializes the first lens-sidecommunication unit 217 and the second lens-side communication unit 218.Likewise, the body control unit 103 first initializes the firstbody-side communication unit 117 and the second body-side communicationunit 118. Through this initialization processing, data communication(command data communication and hotline communication) between thecamera body 100 and the exchangeable lens 200 is enabled.

Having initialized the communication units, the lens control unit 203(initialization control unit 223) starts initialization of the drivetarget members in the exchangeable lens 200. The exchangeable lens 200in the embodiment includes a plurality of drive target members (thefocusing lens 210 b, the blur correction lens 210 c and the aperture211). After power to the camera 1 is turned on, the body control unit103 and the lens control unit 203 cannot execute regular controlprocessing for the drive target members until the initialization controlunit 223 completes execution of specific initialization processing.Examples of the regular control processing include drive conditiontransmission processing executed by the drive condition transmissionunit 222 and drive processing executed by the drive control unit 123.

The initialization control unit 223 in the embodiment sequentiallyexecutes the initialization processing for the individual drive targetmembers by first initializing the aperture 211, then initializing theblur correction lens 210 c and finally initializing the focusing lens210 b. Processing that involves the drive target members cannot beexecuted at the camera body 100 (body control unit 103) until theinitialization processing by the initialization control unit 223 iscompleted. For instance, until the initialization of the aperture 211 iscompleted, the aperture diameter at the aperture 211 cannot be adjustedat the camera body 100 (by the body control unit 103) and thus,processing such as exposure control cannot be executed at the camerabody 100.

In the embodiment, the initialization status transmission unit 221transmits initialization status data indicating the initializationstatus of each drive target member to the camera body 100(initialization status reception unit 121) over predetermined cycles.The body control unit 103 engages the initialization status receptionunit 121 in operation so as to read the initialization status datahaving been received and sequentially starts control processing fordrive target members for which initialization processing has beencompleted. In other words, the drive control unit 123 does not executethe control processing for any drive target member the initializationstatus data for which indicate that the execution of the initializationprocessing is still incomplete.

FIGS. 6A and 6B show the structure of information (data) indicating aninitialization status. Upon completing the initialization of theindividual communication units, the body control unit 103 transmits aninitialization status request command (data) 50 shown in FIG. 6A fromthe first body-side communication unit 117 to the exchangeable lens 200over predetermined cycles. Upon receiving this initialization statusrequest command (data) 50, the first lens-side communication unit 217transmits initialization status information (data) 60 shown in FIG. 6Bto the first body-side communication unit 117. Namely, theinitialization status transmission unit 221 transmits the initializationstatus information (data) 60 indicating whether or not execution of theinitialization processing for each of the plurality of drive targetmembers has been completed to the first body-side communication unit 117via the first lens-side communication unit 217 over the predeterminedcycles (e.g., over 16 ms cycles). The body-side command packet signal402 and the lens-side data packet signal 407 exchanged in the commanddata communication, as shown in FIG. 4 respectively correspond to theinitialization status request command (data) 50 and the initializationstatus information (data) 60.

It is to be noted that an area notated as “N/A” in FIGS. 6A and 6B is anarea not assigned with any specific data. In other words, any data maybe set in the area notated as “N/A”. The first body-side communicationunit 117 and the first lens-side communication unit 217 simply disregardthe data stored in this area.

The initialization status request command (data) 50 shown in FIG. 6A istwo-byte data with an integer 51 indicating the identity of the data,i.e., the initialization request command (data) 50, carried in thelower-order byte. While the identifier integer 51 in the examplepresented in FIG. 6A is a hexadecimal number “60H”, the identifierinteger may take another number, as long as it indicates the identity ofthe data, i.e., the initialization status request command (data) 50.

The initialization status information (data) 60 shown in FIG. 6B istwo-byte data with an integer 61 indicating the identity of the data,i.e., the initialization status information (data) 60, carried in thelower-order byte. A flag 62 indicating whether or not the execution ofthe initialization processing for the aperture 211 has been completed isset in the eighth bit. If the initialization processing for the aperture211 is still incomplete, the initialization status transmission unit 221transmits initialization status information (data) 60 with 0 set at theflag 62. Likewise, a flag 63 indicating whether or not the execution ofthe initialization processing for the blur correction lens 210 c hasbeen completed is set in the ninth bit, and a flag 64 indicating whetheror not the execution of the initialization processing for the focusinglens 210 b has been completed is set in the tenth bit.

FIG. 7 is a time chart indicating the procedure through which theinitialization processing is executed after power is turned on. As apower on operation is performed at the camera 1 at a time point T10, thebody control unit 103 starts initialization processing 71 for theindividual body-side communication units. The lens control unit 203(initialization control unit 223), too, starts initialization processing72 for the individual lens-side communication units.

Upon completing the initialization processing 71 for the communicationunits, the body control unit 103 starts the transmission of theinitialization status request command (data) 50 described earlier.Subsequently, the body control unit 103 repeatedly transmits theinitialization status request command (data) 50 over the predeterminedcycles until control processing 78 executed as described later for thefocusing lens 210 b is completed (i.e., it repeatedly transmits theinitialization status request command (data) 50 during a period Ti).

Upon completing the initialization processing 72 for the communicationunits, the lens control unit 203 (initialization control unit 223)starts initialization processing 73 for the aperture 211. Theinitialization processing 73 executed for the aperture 211 may include,for instance, home position resumption processing for the apertureactuator (not shown) that drives the aperture 211. Through the homeposition resumption processing, the aperture 211 is driven to anaperture maximum open setting (the position at which the aperture 211 isdriven to a contact position with a mechanical regulator present at theaperture maximum side, at which the aperture achieves a fully openstate) by driving the aperture actuator. Until the execution of theinitialization processing 73 for the aperture 211 by the initializationcontrol unit 223 is completed, the lens control unit 203 (initializationstatus transmission unit 221) transmits initialization statusinformation (data) 60 with the flag 62, the flag 63 and the flag 64 allindicating 0 via the first lens-side communication unit 217 (to thecamera body 100) each time the initialization status request command(data) 50 transmitted from the camera body 100 is received.

It is to be noted that one of two different types of processing isexecuted as the initialization processing for the aperture 211. Thefirst type of processing will be referred to as initializationprocessing 1, executed in response to a power on operation (startup) atthe camera having been in a “power off state”, in which the power switchat the camera body 100 is in the off state. The other type of processingwill be referred to as initialization processing 2, executed whenstarting up the camera having been in a “sleep state”, in which thecamera body assumes a power-saving mode while the power switch on thecamera body side remains on. The position assumed by the aperture 211(control aperture position) before entering the sleep state is storedinto a memory within the lens control unit 203 as the camera body shiftsinto the sleep state.

As the initialization processing 1, the home position resumptionprocessing is executed for the aperture actuator (not shown) that drivesthe aperture 211 as described earlier.

In the initialization processing 2, the home position resumptionprocessing is first executed for the aperture actuator as describedabove and then control is executed to drive the aperture 211 to theaperture position (control aperture position) assumed prior to the shiftinto the sleep state, having been stored in the memory within the lenscontrol unit 203.

The body control unit 103, having ascertained the current state of thecamera body, i.e., recognizing the power off state or the sleep state,transmits the information (parameter) indicating whether the lenscontrol unit 203 is to engage in the initialization processing 1 or inthe initialization processing 2, to the lens control unit 203 when itissues an initialization start instruction to the lens control unit 203.Based upon this parameter, the lens control unit 203 executes either theinitialization processing 1 or the initialization processing 2.

Once execution of the initialization processing 73 for the aperture 211is completed (i.e., once the initialization of the aperture 211 iscompleted and the regular aperture control is enabled), theinitialization status transmission unit 221 transmits initializationstatus information (data) 60 with 1 set for the flag 62. Upon receivingthe initialization status information (data) 60 with the flag 62indicating 1, the body control unit 103 engages the drive control unit123 in operation so as to start execution of control processing 74 forthe aperture 211. Types of control processing executed for the aperture211 may include, for instance, photometric calculation processing,through which photometering information needed for exposure control isgenerated based upon the output from the image sensor 104 located in thebody and aperture position information acquisition processing throughwhich the current position of the aperture 211 is detected. In addition,depending upon the photographing mode and photographing conditions suchas the subject brightness indicated in the photometering informationmentioned above, photographic aperture control processing through whichcontrol is executed to adjust the aperture 211 to a control targetphotographic aperture value for the photographing operation may also beexecuted as part of the control processing for the aperture 211.

Following the initialization processing for the aperture 211, the lenscontrol unit 203 (initialization control unit 223) sequentially executesinitialization processing 75 for the blur correction lens 210 c andinitialization processing 77 for the focusing lens 210 b. In otherwords, the lens control unit 203 (initialization control unit 223) inthe embodiment completes the initialization processing for the aperture211 ahead of the initialization processing executed for the other drivetarget members. Each time the initialization processing executed for aspecific drive target member is completed, the initialization statustransmission unit 221 switches the corresponding flag (the flag 63 orthe flag 64) in the initialization status information (data) 60 to betransmitted next from 0 to 1. The body control unit 103 detects such aswitch at the flag (i.e., the completion of the correspondinginitialization processing) and then engages the drive control unit 123in execution of control processing for the drive target member judged tobe ready for control other than the initialization processing based uponthe switch at the particular flag. The control processing executed forthe drive target members includes control processing 76 for the blurcorrection lens 210 c and control processing 78 for the focusing lens210 b. Through the blur correction lens control processing 76, acentering processing operation for centering the blur correction lensand an operation for obtaining the blur correction lens positioninformation indicating the position of the blur correction lens havingbeen centered via the command data communication system rather than thehotline communication system described earlier, may be executed. Throughcontrol processing 78 for the focusing lens 210 b, data related tofocusing processing having been stored in the internal memory at thebody (e.g. defocus information indicating the extent of defocusinghaving been stored for the immediately preceding focusing processing)may be cleared from the memory. Then, as the initialization processingexecuted for the individual drive target members, as indicated in FIG. 7is completed and also all the control processing for the individualdrive target members is completed, the camera 1 executes photographingpreparatory operations (e.g., focusing lens control, blur correctionlens control, aperture control and the like) and subsequently enters aphotographing-enabled state, in response to an operation performed at anoperation member to issue a photographing start instruction (e.g., ahalfway press operation or full press operation at the shutter releasebutton).

As does the initialization processing 73 for the aperture 211 describedearlier, the initialization processing 77 for the focusing lens 210 bincludes home position resumption processing for the focusing lensactuator (not shown) that drives the focusing lens 210 b. Through thishome position resumption processing, the focusing lens 210 b is drivento a reference position (e.g., a telephoto end position or a wide-angleend position) selected in advance for the focusing lens 210 b. It is tobe noted that a decision as to whether or not the focusing lens 210 bhas reached the reference position is made based upon detection resultsprovided by a sensor (a photo interrupter (not shown)) installed in theexchangeable lens, and the lens control unit 203 executes control tostop the focusing lens actuator based upon the detection resultsprovided by the sensor.

It is to be noted that either of the two different types of processing(initialization processing 1 executed in response to a power onoperation (startup operation) performed at the camera having been in the“power off state” and initialization processing 2 executed to startup ofthe camera body in the “sleep state”) is executed as the initializationprocessing 77 for the focusing lens 210 b, as is the case with theinitialization processing 73 for the aperture 211 described earlier.Details of the initialization processing 1 and the initializationprocessing 2 are similar to those of the initialization processing 73executed for the aperture 211 and the only difference is that the drivetarget is the focusing lens 210 b rather than the aperture 211.Accordingly, a repeated explanation is not provided.

Through the initialization processing 75 executed for the blurcorrection lens 210 c, a correction value, to be used to correct theoutput of a position detection sensor that detects the position of theblur correction lens 210 c, is calculated. The position detection sensorused to detect the position of the blur correction lens 210 c in theembodiment is an inexpensive sensor (e.g., a Hall sensor). The output ofsuch a position detection sensor is bound to vary as the ambienttemperature changes. For this reason, the output of the positiondetection sensor needs to be corrected in correspondence to the ambienttemperature so as to ensure that accurate position detection is enabledat any ambient temperature. Through the correction processing executedas part of the initialization processing 75, the correction value iscalculated in correspondence to the ambient temperature and thecorrection value thus calculated is stored in the memory at the lenscontrol unit 203. The processing executed up to the point at which thecorrection value is stored constitutes the initialization processing 75.Then, as the actual position assumed by the blur correction lens 210 cis detected, the output of the position detection sensor that detectsthe position of the blur correction lens 210 c is corrected based uponthe corresponding correction value stored in the memory at the lenscontrol unit 203. It is to be noted that the ambient temperature isdetected via a temperature sensor (not shown) installed on a circuitboard in the lens.

It is to be noted that, in order to save power, home position resumptionprocessing for the blur correction lens 210 c (i.e., processing throughwhich the blur correction lens 210 c is driven to a predeterminedreference position so as to, for instance, align the center of the blurcorrection lens 210 c with the center of the optical axis of theexchangeable lens 200) is not executed as part of the initializationprocessing 75, in the embodiment.

Description of Drive Condition Data

FIG. 8 shows the structure of the drive condition information (data).The drive condition information (data) indicates the drive conditions atthe drive target members in the exchangeable lens 200. The drivecondition transmission unit 222 transmits drive condition information(data) 80 shown in FIG. 8 to the camera body 100 (drive conditionreception unit 122) over predetermined cycles (e.g., 1 ms cycles). Thedrive condition information (data) 80 is transmitted through hotlinecommunication. Namely, the drive condition information (data) 80 istransmitted from the second lens-side communication unit 218 to thesecond body-side communication unit 118 through the second transmissionpath. Once the initialization of all the drive target members iscompleted, the drive condition transmission unit 222 starts transmissionof information indicating the drive conditions at the individual drivetarget members. In other words, until the initialization control unit223 completes the initialization processing for all the drive targetmembers, the transmission of the drive condition information (data) 80does not start. This means that only after the initialization statusreception unit 121 receives the initialization status information (data)60 indicating that the initialization of all the drive target membershas been completed, the drive condition reception unit 122 at the camerabody 100 outputs a request signal to the exchangeable lens 200 throughthe hotline communication system described earlier and thus startsreceiving the drive condition information (data) 80 sent thereto inresponse to the request signal. The sequence through which the drivecondition transmission unit 222 transmits the drive conditioninformation (data) to the camera body 100 over predetermined cycles(over second cycles) is now described. The camera body 100 outputs asignal (request signal) requesting the drive condition information(data) to the exchangeable lens 200 over the second cycles (e.g., 1 mscycles). The drive condition transmission unit 222 at the exchangeablelens 200 responds to the request signal by transmitting drive conditioninformation (data) it has prepared. Through this sequence, the drivecondition transmission unit 222 is able to transmit the drive conditioninformation (data) to the camera body 100 over the predetermined secondcycles.

The drive condition information (data) 80 is four byte data that includeposition data 81 indicating the position of the focusing lens 210 b,opening diameter data 82 indicating the opening diameter assumed at theaperture 211 and position data 83 indicating the position of the blurcorrection lens 210 c. The position data 81 indicate, with a one-byteinteger in a range of 0 through 255, the position of the focusing lens210 b among various positions that may be assumed between the close-upposition and the infinity position, each corresponding to a specificvalue in the 0 through 255 range. Likewise, the opening diameter data 82indicate the opening diameter assumed at the aperture 211 as a one-byteinteger in the range of 0 through 255, among various settings betweenthe maximum aperture setting (maximum opening diameter) and the minimumaperture setting (minimum opening diameter), each corresponding to aspecific value in the 0 through 255 range. The position data 83 indicatethe position of the blur correction lens 210 c with two sets of one-byteinteger data combined together. The position of the blur correction lens210 c assumed on a plane perpendicular to the optical axis of the imageforming optical system 210 is indicated with a value in the 0 through255 range taken along the x-axis and a value in the 0 through 255 rangetaken along the y-axis.

The body control unit 103 obtains the current drive conditions of thevarious drive target members by referencing the drive condition data 80received by the drive condition reception unit 122. Then, based upon thedrive conditions thus ascertained, it engages the drive control unit 123in drive control. For instance, while driving the focusing lens 210 b, adecision as to whether or not the focusing lens 210 b has been driven tothe target position is made by referencing the drive condition data 80.

Description of Processing Executed During a Period Following Power onOperation Until Photographing Operation is Enabled

FIG. 9 presents a flowchart of the processing executed during the periodfollowing a power on operation until the camera enters aphotographing-enabled state. The processing executed by the body controlunit 103 is shown on the left side of FIG. 9, whereas the processingexecuted by the lens control unit 203 is shown on the right side of FIG.9. The processing executed by the body control unit 103 will bedescribed first.

In step S100, the body control unit 103 accepts a power on operationperformed by the user. In step S110, the body control unit 103 executesthe initialization processing for the first body-side communication unit117 and the second body-side communication unit 118. In step S120, thebody control unit 103 outputs a specific lens startup signal to theexchangeable lens 200 via a contact point at the holding portion 102. Instep S130, the body control unit 103 engages the first body-sidecommunication unit 117 in operation so as to transmit a specificinitialization start instruction.

In step S140, the body control unit 103 makes a decision as to whetheror not a predetermined length of time (e.g., 16 ms) has elapsedfollowing the execution of the processing in step S130. The body controlunit 103 repeatedly executes the processing in step S140 until thepredetermined length of time elapses. If it is decided that thepredetermined length of time has elapsed, the processing proceeds tostep S150. In step S150, the body control unit 103 transmits aninitialization status request command (data) 50 to the exchangeable lens200. In step S160, the initialization status reception unit 121 receivesinitialization status information (data) 60. In step S170, the bodycontrol unit 103 makes a decision as to whether or not there has beenany change in the initialization statuses indicated in initializationstatus information (data) 60 having been received previously byreferencing the initialization status information (data) 60 received instep S160 in the current session. If it is decided that theinitialization statuses have not changed, the operation proceeds to stepS140 to wait in standby for a predetermined length of time afterexecution of the processing in step S170. If, on the other hand, it isdecided that a change has occurred in an initialization status, theoperation proceeds to step S180, in which the drive control unit 123executes specific control processing for the drive target member, theinitialization status of which has changed. In step S190, the bodycontrol unit 103 makes a decision as to whether or not all the drivetarget members have been completely initialized. If there is any drivetarget member not yet initialized, the operation returns to step S140 towait for a predetermined length of time after execution of theprocessing in step S190. If, on the other hand, it is decided that theinitialization of all the drive target members has been completed, theoperation proceeds to step S200 to shift the camera body 100 into aphotographing-enabled state.

Next, the processing executed by the lens control unit 203 is described.In step S210, the lens startup signal is input from the camera body 100.The lens control unit 203 begins startup processing in response to thissignal. In step S220, the initialization control unit 223 executesinitialization processing for the first lens-side communication unit 217and the second lens-side communication unit 218. In step S230, the lenscontrol unit 203 receives the initialization start instruction from thecamera body 100. In step S240, the initialization control unit 223sequentially starts initialization processing for the various drivetarget members. The initialization control unit 223 first starts theinitialization processing for the aperture 211, and upon completing theinitialization processing for the aperture 211, it starts initializationprocessing for the other drive target members in sequence. As explainedearlier, the initialization control unit 223 executes the initializationprocessing for one drive target member at a time.

In step S250, the lens control unit 203 makes a decision as to whetheror not an initialization status request command (data) 50 from thecamera body 100 has been received. Until an initialization statusrequest command (data) 50 is received, the lens control unit 203repeatedly executes the processing in step S250. Once an initializationstatus request command (data) 50 is received, the operation proceeds tostep S260. In step S260, the initialization status transmission unit 221transmits initialization status information (data) 60 to the camera body100. In step S270, the lens control unit 203 makes a decision as towhether or not the various flags in the initialization statusinformation (data) 60 having just been transmitted in the preceding stepS260 all indicate “1”. If a negative decision is made in step S270, theoperation returns to step S250. However, if it is decided that all theflags indicate 1 in the initialization status information (data) 60having been transmitted, the operation proceeds to step S280. In stepS280, the lens control unit 203 shifts the exchangeable lens 200 into aphotographing-enabled state.

The following operational effects are achieved with the camera system inthe first embodiment described above.

(1) The initialization control unit 223 executes specific initializationprocessing for each of the drive target members. The initializationstatus transmission unit 221 transmits initialization status information(data), which indicates whether or not the execution of theinitialization processing for each of the drive target members has beencompleted, to the camera body 100. Since the initialization statuses aretransmitted from the exchangeable lens 200 to the camera body 100, thelength of time required to detect the completion of initialization ofthe exchangeable lens can be reduced.

In addition, the initialization status information (data) is transmittedto the camera body 100 via the first transmission path (command datacommunication system) over predetermined cycles (e.g., over 16 mscycles, in response to the request command issued from the camera bodyside over the predetermined first cycles). Since the initializationstatuses are transmitted on a regular basis from the exchangeable lens200 to the camera body 100 over predetermined cycles as described above,the length of time required to detect the completion of initializationof the exchangeable lens can be reduced.

In addition, once the initialization of the individual drive targetmembers is completed, the drive condition transmission unit 222transmits drive condition data, indicating the drive conditions of thedrive target members, to the camera body 100 through the secondtransmission path (hotline communication system) over predeterminedcycles. Through these measures, the conditions of the drive targetmembers can be ascertained at the camera body 100 as soon as theinitialization processing is completed.

(2) The initialization control unit 223 completes the initializationprocessing for the aperture 211 ahead of the initialization processingfor the other drive target members. Through the initializationprocessing executed in the embodiment for the aperture member, theaperture 211 is set to achieve the maximum aperture (initializationprocessing 1) or to achieve the photographing aperture opening havingbeen stored before a shift to the sleep state (initialization processing2). In other words, the aperture 211 is initialized by adjusting it to aphotometering-ready state (the aperture is adjusted for maximum-aperturephotometering or for photographing aperture photometering) correspondingto the current conditions. As a result, the camera body 100 is able tostart preparing for a photometering operation (by executing, forinstance, photometric calculation processing based upon the image sensoroutput as described earlier) without having to wait for theinitialization of the other drive target members to be completed, makingit possible to reduce the length of time required to achieve thephotographing-enabled state.

(3) The initialization status transmission unit 221 in the exchangeablelens 200 transmits initialization status data 60, indicating theinitialization statuses of the drive target members, to the camera body100 over predetermined cycles. Thus, the camera body 100 is able toascertain the statuses of the individual drive target members with ahigh level of accuracy each time it receives the initialization statusdata 60, and is able to execute optimal preparatory operation on thecamera body side in correspondence to the initialization statuses. As aresult, the length of time to elapse before the photographing-enabledstate is achieved can be reduced.

(4) The initialization control unit 223 executes initializationprocessing for the individual drive target members in a predeterminedsequence by executing initialization processing for one drive targetmember at a time. Through these measures, the order with which theexecutions of the initialization processing for the individual drivetarget members are completed can remain unchanged at all times, and, asa result, better ease of control is assured.

(5) The drive condition reception unit 122 starts receiving informationindicating the drive conditions of the drive target members only afterinitialization status data 60 indicating that the initialization of thedrive target members has been completed is received by theinitialization status reception unit 121. As a result, inaccurate drivecondition information regarding a drive target member yet to be fullyinitialized is never received.

(6) The drive control unit 123 does not execute the specific controlprocessing for any drive target member, the execution of theinitialization processing for which is indicated to be incomplete in theinitialization status data 60. Through these measures, it is ensuredthat no incorrect drive control is executed for the drive target memberyet to be fully initialized.

Second Embodiment

The camera system achieved in the second embodiment of the presentinvention adopts a structure similar to that of the camera systemachieved in the first embodiment. The second embodiment differs from thefirst embodiment in the order with which (procedure through which) theinitialization control unit 223 executes initialization processing forthe drive target members. It is to be noted that the second embodimentwill be described by quoting the same reference numerals wheneverreferring to details identical to those of the first embodiment.

FIG. 10 is a time chart indicating the procedure through which theinitialization processing is executed following a power on operation.The initialization control unit 223 in this embodiment concurrentlyexecutes the initialization processing for all the drive target membersafter initialization processing 72 is executed for the communicationunits. Namely, initialization processing 73 for the aperture 211,initialization processing 75 for the blur correction lens 210 c andinitialization processing 77 for the focusing lens 210 b are all startedat once. The length of time required for execution of the initializationprocessing is different for each of the drive target members and,accordingly, the body control unit 103 starts executing the controlprocessing for each drive target member as soon as the initialization ofthe particular drive target member is completed. For instance, as theaperture initialization processing 73 ends first, execution of aperturecontrol processing 74 immediately starts, as shown in FIG. 10. Then,once execution of the aperture control processing 74 is completed, thebody control unit 103 waits in standby for completion of execution ofthe initialization processing for another drive target member.Subsequently, each time execution of the initialization processing iscompleted, the corresponding control processing (e.g., blur correctionlens control processing 76 or focusing lens control processing 78) isexecuted.

It is to be noted that as has been described in reference to the firstembodiment, either of the two different types of processing (i.e., theprocessing executed when starting up from the power off state and theprocessing executed when starting up from the sleep state) is executedas the initialization processing 73 and also as the initializationprocessing 77.

The operational flow followed in the second embodiment is substantiallyidentical to the operational flow shown in FIG. 9. The operational flowin the second embodiment is distinguishable from the operational flow inthe first embodiment shown in FIG. 9 in that the initialization controlunit 223 “simultaneously starts” the initialization processing for theindividual drive target members in step S240 in the second embodiment.

In addition to the operational effects of the camera system in the firstembodiment, the following operational effects are achieved with thecamera system in the second embodiment described above.

(1) The initialization control unit 223 simultaneously starts executionof the initialization processing for the plurality of drive targetmembers. Since the initialization processing for the different drivetarget members is executed concurrently, the overall length of timerequired to complete the initialization of all the drive target memberscan be reduced, which, in turn, makes it possible to shorten the lengthof time to elapse before the photographing-enabled state is achieved.

(2) The initialization control unit 223 simultaneously starts executionof the initialization processing for the plurality of drive targetmembers. Each time the initialization processing for a given drivetarget member is completed, the exchangeable lens 200 transmitsinformation indicating the completion of the particular initializationprocessing to the camera body side. As a result, the camera body is ableto immediately ascertain the completion of the initialization processingfor a particular drive target member and is thus able to start camerabody-side photographing preparatory operations in a sequence matchingthe order with which the individual drive target members become fullyinitialized. As a result, the length of time to elapse before thephotographing-enabled state is achieved can be further reduced.

The present invention allows for the following variations and one of thevariations or a plurality of variations may be adopted in combinationwith either of the embodiments described above.

Variation 1

In either of the embodiments described above, the drive conditiontransmission unit 222 does not transmit the drive condition informationuntil the initialization for all the drive target members is completed.As an alternative, it may start transmitting the drive conditioninformation in sequence by transmitting the drive condition informationfor a drive target member as soon as the initialization thereof iscompleted. For instance, variable length data may be used as the drivecondition data 80, and the transmission of information related to theopening aperture at the aperture 211 alone may be enabled so as to starttransmitting information indicating the drive conditions of the aperture211 as soon as initialization of the aperture 211 is completed.

Variation 2

A member other than the aperture, the focusing lens or the blurcorrection lens may be designated as a drive target member. In addition,the drive target members may be initialized in an order different fromthe order in which they are initialized in the embodiments describedabove.

Variation 3

The exchangeable lens 200 in the embodiments is configured so as totransmit drive condition information indicating the drive conditions ofthe plurality of drive target members as drive target member drivecondition information to be sent to the camera body side through thehotline communication system (see FIG. 8). However, the presentinvention is not limited to an application in which drive conditioninformation for a plurality of drive target members is transmitted, andit may instead be adopted in an application in which drive conditioninformation indicating the drive conditions of one of the plurality ofdrive target members is transmitted. Furthermore, it may be adopted inconjunction with an exchangeable lens 200 that includes only one drivetarget member.

Variation 4

The exchangeable lens 200 in the embodiments is configured so as totransmit the initialization status data 60 to the camera body 100 overthe predetermined first cycles through the command data communicationsystem. As an alternative, the camera body side may be notified of anychange in the status of the initialization processing more quickly untilthe initialization processing at the exchangeable lens 200 is completed.For instance, until the initialization processing executed for all thedrive target members is completed at the exchangeable lens 200, thecommunication cycles through the command data communication system maybe shortened. In more specific terms, control may be executed so as toshorten the communication cycles, over which the camera body 100 and theexchangeable lens 200 communicate with each other through the commanddata communication system, relative to the predetermined first cycles.Since this allows the camera body 100 to be notified immediately thatthe initialization processing for each drive target member has beencompleted, the length of time to elapse before the photographingpreparatory operations are executed and the length of time to elapsebefore the photographing operation is executed can be reduced.

Variation 5

In the initialization processing 75 executed for the blur correctionlens 210 c in the embodiments, the blur correction lens 210 c may bedriven to a reference position. For instance, the blur correction lens210 c may be driven so as to align the center of the blur correctionlens 210 c with the optical axis of the photographic lens 200 throughthe initialization processing 75. Such home position resumptionprocessing may be incorporated into the initialization processing 75 forthe blur correction lens 210 c as long as sufficient battery power isavailable on the camera body side.

Variation 6

While the initialization processing 73, the initialization processing 75and the initialization processing 77 for the three different drivetarget members are started simultaneously in the second embodimentdescribed above, the present invention is not limited to this exampleand the initialization processing for any two drive target members maystart simultaneously with the initialization processing for theremaining one drive target member started with different timing.

Variation 7

Each time the initialization processing status corresponding to a givendrive target member changes (each time the initialization processing fora drive target member ends), information indicating the change istransmitted to the camera body side in the embodiments described above.However, the present invention is not limited to this example. Forinstance, the present invention may be adopted in a camera system inwhich information indicating the initialization processing for all thedrive target members has not yet been completed (e.g., informationindicating the entire initialization processing has not yet beencompleted, with the flags 62 through 64 in the initialization statusdata 60 in FIG. 6 all indicating “0”) may be transmitted from theexchangeable lens side until the initialization processing for all thedrive target members undergoing initialization is completed. In thiscase, upon completing the initialization processing for all the drivetarget members, information indicating that the initializationprocessing for all the drive target members has been completed, with,for instance, the flags 62 through 64 all indicating “1” in theinitialization status data 60 in FIG. 6 will be transmitted. Thisstructure, too, allows the exchangeable lens to indicate to the camerabody the completion of the entire initialization processing as soon asit is completed.

As described above, the length of time required for initialization ofthe exchangeable lens can be reduced by adopting any of the embodimentsof the present invention or any variation thereof.

As long as the features characterizing the present invention are notcompromised, the present invention is not limited to the particulars ofthe embodiments described above and other modes that are conceivablewithin the technical scope of the present invention are also within thescope of the invention.

What is claimed is:
 1. A camera accessory that is attachable to a camerabody, the camera accessory comprising: an aperture, a drive condition ofwhich changes as a drive force is applied thereto; a focusing lens, adrive condition of which changes as a drive force is applied thereto; afirst contact via which information, indicating that initializationprocessing for the aperture and the focusing lens has been completed, istransmitted to the camera body; and a second contact via whichinformation indicative of the drive condition of one of the aperture andthe focusing lens is transmitted to the camera body without informationindicative of the drive condition of another of the aperture and thefocusing lens after the information indicating that the initializationprocessing for the aperture and the focusing lens has been completed istransmitted via the first contact.
 2. The camera accessory according toclaim 1, wherein: the information indicative of the drive condition ofthe focusing lens is information indicative of a position of thefocusing lens.
 3. The camera accessory according to claim 1, wherein:the initialization processing for the aperture includes at least one ofa first processing in which the aperture is driven so as to adjust anopening of the aperture to a first value, and a second processing inwhich the aperture is driven so as to adjust the opening of the apertureto a second value different from the first value after the opening ofthe aperture is adjusted to the first value.
 4. The camera accessoryaccording to claim 1, wherein: the initialization processing for thefocusing lens includes at least one of a third processing in which thefocusing lens is driven to a position assuming a third value, and afourth processing in which the focusing lens is driven to a positionassuming a fourth value different from the third value after thefocusing lens is driven to the position assuming the third value.
 5. Thecamera accessory according to claim 1, further comprising: a blurcorrection lens, a drive condition of which changes as a drive force isapplied thereto, wherein: transmission of the information indicative ofthe drive condition of the one of the aperture and the focusing lens isstarted via the second contact after information indicating thatinitialization processing for the aperture, the focusing lens and theblur correction lens has been completed is transmitted to the camerabody via the first contact.
 6. A camera accessory that is attachable toa camera body, the camera accessory comprising: an aperture, a drivecondition of which changes as a drive force is applied thereto; afocusing lens, a drive condition of which changes as a drive force isapplied thereto; a first contact via which information, indicating thatinitialization processing for the aperture and the focusing lens hasbeen completed, is transmitted to the camera body; and a second contactvia which transmission of the drive condition of the focusing lens tothe camera body is started after the information indicating that theinitialization processing for the aperture and the focusing lens hasbeen completed is transmitted via the first contact.
 7. The cameraaccessory according to claim 6, wherein: the drive condition of theaperture is not transmitted via the second contact.
 8. The cameraaccessory according to claim 6, wherein: the drive condition of thefocusing lens includes information of a position of the focusing lens.9. The camera accessory according to claim 6, wherein: theinitialization processing for the aperture includes at least one of afirst processing in which the aperture is driven so as to adjust anopening of the aperture to a first value, and a second processing inwhich the aperture is driven so as to adjust the opening of the apertureto a second value different from the first value after the opening ofthe aperture is adjusted to the first value.
 10. The camera accessoryaccording to claim 6, wherein: the initialization processing for thefocusing lens includes at least one of a third processing in which thefocusing lens is driven to a position assuming a third value, and afourth processing in which the focusing lens is driven to a positionassuming a fourth value different from the third value after thefocusing lens is driven to the position assuming the third value. 11.The camera accessory according to claim 6, further comprising: a blurcorrection lens, a drive condition of which changes as a drive force isapplied thereto, wherein: transmission of the information indicative ofthe drive condition is started via the second contact after informationindicating that initialization processing for the aperture, the focusinglens and the blur correction lens has been completed is transmitted tothe camera body via the first contact.
 12. The camera accessoryaccording to claim 1, wherein: in the initialization processing for thefocusing lens, the focusing lens is driven to a predetermined positionby the drive force.
 13. The camera accessory according to claim 1,wherein: in the initialization processing for the aperture, an openingsize of the aperture is adjusted to a predetermined value by the driveforce.
 14. The camera accessory according to claim 6, wherein: in theinitialization processing for the focusing lens, the focusing lens isdriven to a predetermined position by the drive force.
 15. The cameraaccessory according to claim 6, wherein: in the initializationprocessing for the aperture, an opening size of the aperture is adjustedto a predetermined value by the drive force.